"Poly vinylidene chloride ("PVDC") coated" polyester films are known and are often used as heat-sealable packaging films. However, halogenated films and coatings are increasingly coming under environmental attack and are being subjected to increasing government regulation. Also, such films generally have a rather narrow heat-sealing range (generally about 30-50.degree. C.)--1. above this range, the package film has a tendency to tear, and 2. below this range, the packaged product may have a tendency to leak.
One possible solution to these problems is to replace the PVDC heat seal coating with other heat seal compositions. However, many heat seal compositions, such as copolyesters, can seal extremely tightly (depending upon the heat seal temperature) and thereby provide a package which is very difficult to open.
The present invention is an innovative solution to the above problems.